Movement: Laying on your back, begin by retracting and depressing your shoulder blades (bring them together and down) and rest with your upper arm on the floor at 90 degrees from your torso. Starting with your forearms vertical, slowly bring them towards the floor while keeping your upper arms in contact with the ground. Do not allow your shoulders to raise up off the floor. Descend as far as is comfortable while maintaining proper shoulder and upper arm position. Hold for time, and do not apply too much force - an aggressive stretch is unnecessary and unwanted here.
Instructions and effects for the Lying Internal Rotation Stretch exercise 
Movement in Frontal and Transverse Planes